Ben Carson denied any involvement with the nutritional supplements firm Mannatech, then admitted he’d taken money from them to endorse their products, then denied it again.

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CNBC’s Carl Quintanilla was lustily booed by the GOP debate audience Wednesday night for pressing Ben Carson on his relationship with a sketchy nutritional supplements firm. The jeers rained so loudly that Carson couldn’t even finish his answer to the question. Which is good for him, because he was in the process of spinning one of the most convoluted, nonsensical, bald-faced lies of the entire campaign. And that’s saying something.

The question was about Carson’s 10-year involvement with a sketchy multilevel marketing firm called Mannatech. As Quintanilla noted, Mannatech has faced scrutiny over its claims that its vitamins could cure everything from autism to cancer, and it paid $7 million to settle deceptive advertising charges brought by the Texas attorney general. Slate’s Helaine Olen has also explained how companies like Mannatech prey on the poor, desperate, and gullible by promising riches if they enroll as direct-sales associates hawking the company’s products. Quintanilla asked Carson a simple question: Why would he continue to be involved with such a company?

Carson’s answer started out equally simple. And then it got complicated. And then he tried to make it simple again. And he was fibbing pretty much the entire time. You can watch the full exchange below. It’s really quite something:

“That’s easy to answer,” said the candidate, who has recently emerged as the leading Republican candidate for president. “I didn’t have any involvement with them. That is total propaganda. And this is what happens in our society: total propaganda.”

Got that? Zero involvement. Total propaganda.

Oh sure, Carson hedged, “I did a couple speeches for them. … They were paid speeches.” But! “It is absolutely absurd to say that I had any kind of a relationship with them.”

At that point, remarkably, Carson decided the moment was right to go ahead and plug the company on national TV. “Do I take the product? Yes. I think it’s a good product.”

A flustered Quintanilla broke in, pointing out that Carson had in fact appeared on Mannatech’s home page until just a week ago, touting the company’s products in a video with the Mannatech logo behind him.

“They did it without my permission,” Carson replied. OK then!

Mystified and at a loss—as the CNBC moderators often were when candidates responded to their questions with denials, falsehoods, and misdirection—Quintanilla asked weakly whether Carson’s claimed ignorance didn’t at least speak to a failure of vetting or judgment. Carson was about to repeat his claim that he had no idea he was on the company’s website when the boos cascaded down from the seats, directed at Quintanilla.